The GT classes of sports car racing offer some of the most
exciting and diverse forms of Motorsport, with many road-based cars of
different specifications often sharing the track at the same time. This leads
to great racing, but understanding the differences between them can be difficult.
Here I will attempt to differentiate between the GT classes, so that you may
enjoy the sport more fully.

For the sake of clarity,
we will stick to classes that currently exist. Attempting to research/explain
GT classes before this point will get fairly confusing. I know this because I
initially tried, and I got a headache.

GTE

GTE is currently the highest level of GT racing, and is
further split into two levels, Pro and Am.
GTE-Pro is largely defined by manufacturers and factory backed teams,
and GTE-Am is for privateers. GTE-Am cars are required to be at least one year
old or made to the previous year's specification. This category was called GT2
before 2011, and is called GTLM in the United SportsCar Championship.

GTE cars must meet certain specifications designed to keep
them closely related to the road cars they are based on. This is known as
homologation. In order for a car to qualify, a large manufacturer (like GM)
must produce at least one road going version of the car per week, or one car a
month for small manufacturers (like Ferrari). These cars must also be available
for sale, with an official launch campaign for the road car and network through
which the car can be sold. The cars must have only two doors, a two or 2+2
seating configuration, and have bona fide sporting ambitions. The car is not
required to use the engine it is offered with (although it usually is), but it
is required to be a production engine used in a road car. Carbon fiber,
titanium and magnesium cannot be used outside of parts like spoilers and
wheels, unless the road car has a carbon cockpit. All cars are
rear-wheel-drive, and engine-based traction control is allowed. Also, in an interesting nod to the Le Mans
era of old, every GTE car is required to have 150 cubic decimeters of luggage
space.

FIA World Endurance Championship
United SportsCar Championship
European Le Mans Series
Asian Le Mans Series
International GT Open

How Much Does a GTE Car Cost?

Cars in this spec will cost you about$750,000.

GT3

GT3 was initially launched in 2005 by the FIA, and was
designed to fit under the GT2 specification. This category was designed to be
much simpler and easier to drive than the GT1 and GT2 classes, so that amateurs
and younger drivers could work their way up into higher levels of GT racing.
This class has become the most popular class of GT racing in the world as it is
present in most regional racing series all over the globe. In the United SportsCar Championship, GT3
cars are run in the GTD class with a different spec- rear wing.

GT3 cars have no limit on engine sizes and configurations,
chassis construction, or layout, but they must be based on road cars that are
in mass production, and a large variety of cars have been homologated. Occasionally
you will see privateers run older GT3 cars, even if they are not in production
anymore.

These cars have all been homologated for use in GT3, in
alphabetical order. Some are no longer in use, but are still technically legal
for use in GT3 races, even if they are not necessarily competitive. Those that
have had their homologation expired are noted as such.

GT3 was designed to be cheaper to run, but a GT3 car will still set you back $420,000

GT4

The GT4 class was created to support the GT3 class with a
true low tech amateur sports car series. The GT4 class consists of cars that
are much closer to the road cars they are based on over than the other classes
featured here. GT4 cars are often referred to as "Track Day" cars, as they are
at price points that make them very accessible to gentleman drivers who want
racing experience. The GT4 class is often seen accompanying GT3 classes in
series around the globe. You'll also see GT4 class cars compete in single make
series.

Cars are adjusted to have an almost identical performance
level so that driver skill is highlighted, and once a car has been homologated it
cannot be modified. This prevents a war of developmental cost increases,
allowing the series to keep it a true amateur series.

There are many more racing series that use the GT4 class or
feature cars built to this spec, so if you know of any more, let me know.

How Much Does a GT4 Car Cost?

For the price of an exotic road car, you can get yourself a race ready GT4 car at around $250,000.

I hope that this helps you understand the current world of
GT racing a bit more. Sometime in the future, I'll write a post about how GT racing got to
this point, but this is how it exists now. I did not include the Japanese GT500 class of Super GT and German DTM as a part of this guide, because those cars are Silhouette cars; while they may look like their road going counterparts, they actually have carbon fiber monocoques and tube frames, and share as much in common with their road going counterparts as Australian V8 Supercars.